1. Field of the Invention
The invention relates to a charger which charges a rechargeable battery built in a portable electronic device such as a mobile phone through a USB interface.
2. Description of the Related Art
Recently, for realizing a smaller and lighter charger, there is used a charger which charges a rechargeable battery built in a portable electronic device by using a DC5V power supply supplied from a Vbus terminal which serves as a power supply terminal of a USB (Universal Serial Bus) which is widely used as a serial bus of a personal computer.
Japanese Patent Application publication No. 2007-60778 discloses a charger using a Vbus terminal of a USB, which realizes a high enough charging current without concern about an electric current value of a Vbus terminal used in other peripheral device connected to a USB interface.
Furthermore, for safety, a portable electronic device provided with a dedicated charger which is unchargeable without authentication is prevailing. Two types are known, i.e., devices made by Apple Computer, Inc. (iPod/iPhone/iPad) and smartphone type devices made by other manufacturers.
However, since the authentication method of the portable electronic devices made by Apple Computer, Inc. and the authentication method of the smartphone type portable electronic devices made by other manufacturers than Apple Computer, Inc. are different, it is necessary to provide a dedicated charger for each or a conversion adapter. This leads to cost increase for users and also causes inconvenience to users since users need keep a conversion adapter.